1. Field of the Invention
The present invention relates to an image forming apparatus, for example, an electrophotography type, an electrostatic recording type image forming apparatus, or the like, and more particularly, to a color image forming apparatus such as a color copying machine, a color printer, or a similar apparatus, wherein a plurality of image forming members are provided to form a plurality of images, each different in color, on respective image storing members, and then these images are transferred, one on another, in turn, on the same recording sheet, held and transported by a recording sheet transporting member.
2. Description of the Related Art
In an image forming apparatus which includes an endless transporting belt having a seam and which transfers an image to a recording sheet held on the transporting belt from a photosensitive drum, if image transferring is performed when the recording sheet is located on the seam, a portion of the image may not be transferred on the recording sheet, resulting in a poor image.
In order to solve the problem, there has been proposed an image forming apparatus (for example, Japanese Unexamined Laid-open Patent Publication No. H5(1993)-2347) with a seam detector provided to detect the seam of the transporting belt. Based on the seam position detected by the seam detector and the size of the recording sheet, the feeding of the recording sheet to the transporting belt is controlled so that the recording sheet is not located on the seam.
However, in the above-mentioned conventional image forming apparatus, the recording sheet is always fed so as not to be located on the seam regardless of the type of the recording sheet. Accordingly, even relatively thick recording sheets such as an OHP film or a cardboard, which are seldom affected by the seam, are always fed on the transporting belt so as to always avoid the seam, which results in a decreased productivity for the whole apparatus.